Lecture 8

Question 1

Define Translesional polymerases

Answer 1

Allow polymerases to skip over distortions/dimers but often result in mutations

Question 2

Describe Short Telomere syndrome, and list it’s effects

Answer 2

Accelerated aging syndrome caused by inheritable gene mutations resulting in decreased telomere length

Harms organs with high cell turnover like bone marrow, liver, lungs, and immune system

Causes premature graying of hair

Discovered with flow cytometry fluorescence techniques

Question 3

Describe Xeroderma Pigmentosum, and list it’s effects

Answer 3

Nucleotide excision repair is afflicted and pyrimidine dimers can no longer be effectively repaired.

This causes UV sensitivity, increased chance of skin cancer, and neurological abnormalities.

treatment includes avoiding sun/radiation exposure

Question 4

Describe Ataxia-telangiectasia, and list it’s effects

Answer 4

ATM protein is afflicted and patients then become hypersensitive to radiation because cells with damaged DNA cannot stop the cell cycle with the ATM protein’s function.

Causes leukemia, lymphoma, gamma ray sensitivity, and genome instability

Present with Ataxic gait, due to the damage the disease causes in the cerebellum

Autosomal recessive disease and 2 hit hypothesis can cause this, where carriers of the disease have the mutation occur on their only good gene, and then they develop ataxia-telangiectasia

Question 5

Describe Bloom Syndrome, and list it’s effects

Answer 5

RecQ helicases are afflicted so the DNA helicase needed for recombination (BLM) is afflicted as well

Cancer at several sites, stunted growth, genome instability

Beak nose, butterfly rash, disproportionately small head

Autosomal recessive ; BLM

Question 6

Define Telemerase

Answer 6

A ribonucleoprotein enzyme complex that builds new telomere sequences onto the ends of chromosomes.

Composed of TERT (telomere reverse transcriptase) and it’s RNA template TERC

Question 7

Define RecQ Helicases

Answer 7

Complexes that function as interface between DNA replication to repair damaged replication forks. “caretakers of the genome” that maintain genomic stability.

Question 8

What is BLM?

Answer 8

it is a type of helicase that is not coded for in patients with Bloom syndrome

Question 9

What is ATM and what is it’s role?

Answer 9

it is a major kinase (alongside ATR) that signals replication stress.

When this doesn’t work, Ataxia Telangiectasia occurs

Question 10

define replication stress

Answer 10

slowing or stalling in replication fork progression